Ablation apparatus and system to limit nerve conduction

ABSTRACT

An electrosurgical probe including a probe body which defines a longitudinal probe axis. The electrosurgical probe also includes a first and second conductive electrode, each disposed along the probe axis. The surface area of the first conductive electrode is greater of the surface area of the second conductive electrode. The ratio of the surface area of the first conductive electrode to the surface area of the second conductive electrode may be adjustable. Another aspect of the present invention is an electrosurgical probe having a probe body which defines a single longitudinal probe axis. The electrosurgical probe of this aspect of the invention further includes more than two electrodes operatively disposed at separate and distinct positions along the axis of the probe body. The electrodes may be selectively connected to one of or a combination of a stimulation energy source, an ablation energy source or a ground for either energy source. Another aspect of the present invention is a method of placing an electrosurgical probe such as described above for specific ablation procedures.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No. 10/870,202, filed Jun. 17, 2004, entitled “Ablation apparatus and system to limit nerve conduction,” now published, which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a method and device used in the field of Minimally Invasive Surgery (or MIS) for interrupting the flow of signals through nerves. These nerves may be rendered incapable of transmitting signals either on a temporarily (hours, days or weeks) or a permanent (months or years) basis. One embodiment of the apparatus includes a single puncture system which features electrodes capable of creating areas of nerve destruction, inhibition and ablation.

BACKGROUND OF THE INVENTION

The human nervous system is used to send and receive signals. The pathway taken by the nerve signals conveys sensory information such as pain, heat, cold and touch and command signals which cause movement (e.g. muscle contractions).

Often extraneous, undesired, or abnormal signals are generated (or are transmitted) along nervous system pathways. Examples include, but are not limited to, the pinching of a minor nerve in the back, which causes extreme back pain. Similarly, the compression or other activation of certain nerves may cause referred pain. Certain diseases also may compromise the lining of nerves such that signals are spontaneously generated, which can cause a variety of maladies, from seizures to pain or (in extreme conditions) even death. Abnormal signal activations can cause many other problems including (but not limited to) twitching, tics, seizures, distortions, cramps, disabilities (in addition to pain), other undesirable conditions, or other painful, abnormal, undesirable, socially or physically detrimental afflictions.

In other situations, the normal conduction of nerve signals can cause undesirable effects. For example in cosmetic applications the activation of the corrugator supercilli muscle causes frown lines which may result in permanent distortion of the brow (or forehead); giving the appearance of premature aging. By interruption of the corrugator supercilli activation nerves, this phenomenon may be terminated. Direct surgical interruption of nerves is however a difficult procedure.

Traditional electrosurgical procedures use either a unipolar or bipolar device connected to that energy source. A unipolar electrode system includes a small surface area electrode, and a return electrode. The return electrode is generally larger in size, and is either resistively or capacitively coupled to the body. Since the same amount of current must flow through each electrode to complete the circuit; the heat generated in the return electrode is dissipated over a larger surface area, and whenever possible, the return electrode is located in areas of high blood flow (such as the biceps, buttocks or other muscular or highly vascularized area) so that heat generated is rapidly carried away, thus preventing a heat rise and consequent burns of the tissue. One advantage of a unipolar system is the ability to place the unipolar probe exactly where it is needed and optimally focus electrosurgical energy where desired. One disadvantage of a unipolar system is that the return electrode must be properly placed and in contact throughout the procedure. A resistive return electrode would typically be coated with a conductive paste or jelly. If the contact with the patient is reduced or if the jelly dries out, a high-current density area may result, increasing the probability for burns at the contact point.

Typical bipolar electrode systems are generally based upon a dual surface device (such as forceps, tweezers, pliers and other grasping type instruments) where the two separate surfaces can be brought together mechanically under force. Each opposing surface is connected to one of the two source connections of the electrosurgical generator. Subsequently, the desired object is held and compressed between the two surfaces. When the electrosurgical energy is applied, it is concentrated (and focused) so that tissue can be cut, desiccated, burned, killed, stunned, closed, destroyed or sealed between the grasping surfaces. Assuming the instrument has been designed and used properly, the resulting current flow will be constrained within the target tissue between the two surfaces. One disadvantage of a conventional bipolar system is that the target tissue must be properly located and isolated between these surfaces. Also, to reduce extraneous current flow the electrodes can not make contact with other tissue, which often requires visual guidance (such as direct visualization, use of a scope, ultrasound or other direct visualization methods) so that the target tissue is properly contained within the bipolar electrodes themselves, prior to application of electrical energy.

In recent years, considerable efforts have been made to refine sources of RF or electrical energy, as well as devices for applying electrical energy to specific targeted tissue. Various applications such as tachyarrhythmia ablation have been developed, whereby accessory pathways within the heart conduct electrical energy in an abnormal pattern. This abnormal signal flow results in excessive and potentially lethal cardiac arrhythmias. RF ablation delivers electrical energy in either a bipolar or unipolar configuration utilizing a long catheter, similar to an electrophysiology (EP) catheter. An EP catheter consisting of a long system of wires and supporting structures normally introduced via an artery or vein which leads into the heart is manipulated using various guidance techniques, such as measurement of electrical activity, ultrasonic guidance, and/or X-ray visualization, into the target area. Electrical energy is then applied and the target tissue is destroyed.

A wide variety of technology in the development of related systems, devices and EP products has already been disclosed. For example, U.S. Pat. No. 5,397,339, issued Mar. 14, 1995, describes a multipolar electrode catheter, which can be used to stimulate, ablate, obtain intercardiac signals, and can expand and enlarge itself inside the heart. Other applications include the ability to destroy plaque formations in the interior of lumens within the body; using RF energy applied near, or at the tip of, catheters such as described in U.S. Pat. No. 5,454,809 and U.S. Pat. No. 5,749,914. In these applications a more advanced catheter which is similar to the EP catheters described above contains an array of electrodes that are able to selectively apply energy in a specific direction. Such devices allow ablation and removal of asymmetric deposits or obstructions within lumens in the body. U.S. Pat. No. 5,098,431 discloses another catheter based system for removing obstructions from within blood vessels. Parins, in U.S. Pat. No. 5,078,717 discloses yet another catheter to selectively remove stenotic lesions from the interior walls of blood vessels. Auth in U.S. Pat. No. 5,364,393 describes a modification of the above technologies whereby a small guide wire which goes through an angioplasty device and is typically 110 cm or longer has an electrically energized tip, which creates a path to follow and thus guides itself through the obstructions.

In applications of a similar nature, catheters which carry larger energy bursts, for example from a defibrillator into chambers of the heart have been disclosed. These catheters are used to destroy both tissues and structures as described in Cunningham (U.S. Pat. No. 4,896,671).

Traditional treatments for the elimination of glabellar furrowing have included surgical forehead lifts, resection of corrugator supercilli muscle, as described by Guyuron, Michelow and Thomas in Corrugator Supercilli Muscle Resection Through Blepharoplastylncision., Plastic Reconstructive Surgery 95 691-696 (1995). Also, surgical division of the corrugator supercilli motor nerves is used and was described by Ellis and Bakala in Anatomy of the Motor Innervation of the Corrugator Supercilli Muscle: Clinical Significance and Development of a New Surgical Technique for Frowning., J Otolaryngology 27; 222-227 (1998). These techniques described are highly invasive and sometimes temporary as nerves regenerate over time and repeat or alternative procedures are required.

More recently, a less invasive procedure to treat glabellar furrowing involves injection of botulinum toxin (Botox) directly into the muscle. This produces a flaccid paralysis and is best described in The New England Journal of Medicine, 324:1186-1194 (1991). While minimally invasive, this technique is predictably transient; so, it must be re-done every few months.

Specific efforts to use RF energy via a two needle bipolar system has been described by Hernandez-Zendejas and Guerrero-Santos in: Percutaneous Selective Radio-Frequency Neuroablation in Plastic Surgery, Aesthetic Plastic Surgery, 18:41 pp 41-48 (1994) The authors described a bipolar system using two parallel needle type electrodes. Utley and Goode described a similar system in Radio-frequency Ablation of the Nerve to the Corrugator Muscle for Elimination of Glabellar Furrowing, Archives of Facial Plastic Surgery, January-March, 99, VI P 46-48, and U.S. Pat. No. 6,139,545. These systems were apparently unable to produce permanent results possibly because of limitations inherent in a two needle bipolar configuration. Thus, as is the case with Botox, the parallel needle electrode systems would typically require periodic repeat procedures.

There are many ways of properly locating an active electrode near the target tissue and determining if it is in close proximity to the nerve. Traditional methods in the cardiac ablation field have included stimulation by using either unipolar and bipolar energy by means of a test pacemaker pulse prior to the implantation of a pacemaker or other stimulation device. A method of threshold analysis called the ‘strength duration curve’ has been used for many years. This curve consists of a vertical axis (or Y-axis) typically voltage, current, charge or other measure of amplitude, and has a horizontal axis (or X-axis) of pulse duration (typically in milliseconds). Such a curve is a rapidly declining line, which decreases exponentially as the pulse width is increased.

Various stimulation devices have been made and patented. One process of stimulation and ablation using a two-needle system is disclosed in U.S. Pat. No. 6,139,545. The stimulation may also be implemented negatively, where tissue not responsive to stimulation is ablated as is described in U.S. Pat. No. 5,782,826 (issued Jul. 21, 1998).

SUMMARY OF THE INVENTION

One aspect of the present invention is an electrosurgical probe including a probe body which defines a longitudinal probe axis. Thus the probe resembles a single needle and can be placed into tissue through a single opening. The electrosurgical probe also includes a first and second conductive electrode, each disposed along the probe axis. The surface area of the first conductive electrode is, in this aspect of the invention, greater than the surface area of the second conductive electrode. The ratio of the surface area of the first conductive electrode to the surface area of the second conductive electrode may be equal to or greater than 3:1 or equal to or greater than 8:1. The ratio of the surface area of the first conductive electrode to the surface area of the second conductive electrode may be adjustable.

The electrosurgical probe of the subject invention may further include a stimulation energy source in electrical communication with either the first or the second conductive electrode. Similarly, the electrosurgical probe may also include an ablation energy source communicating with either the first or second conductive electrode. A switch may be provided for the selective connection of the stimulation energy source or the ablation energy source to at least one of the conductive electrodes. Either the first or the second conductive electrode may be nearer the point of the electrosurgical probe at one end of the probe axis.

Another aspect of the present invention is an electrosurgical probe including a probe body defining a longitudinal probe axis, an active electrode operatively associated with the probe body at a first location along the probe axis, a stimulation electrode associated with the probe body at a second location along the probe axis and a return electrode operatively associated with the probe body at a third location along the probe axis. The stimulation electrode may be positioned between the active and return electrodes. The electrosurgical probe of this embodiment may further include a stimulation energy source in electrical communication with the stimulation electrode. The stimulation energy source may provide variable stimulation current. Either the active electrode, the return electrode or both may be connected to a ground for the stimulation energy source. Alternatively, a separate ground may be employed. This aspect of the present invention may also include an ablation energy source connected to the active electrode. The ablation energy source may be configured to provide variable ablation energy.

Another aspect of the present invention is an electrosurgical probe also having a probe body defining a longitudinal probe axis. At least three electrodes will be associated with the probe body at distinct and separate locations along the probe axis. A stimulation energy source connected to at least one of the electrodes is also included.

The stimulation energy source of this embodiment of the present invention may be configured to provide variable stimulation energy. In addition, the stimulation energy source may be selectively connected by means of a switch to at least one or more of the various electrodes. Similarly, a ground for the stimulation energy source may be selectively connected to one or more of the electrodes.

Another aspect of the present invention is a method for positioning an electrosurgical probe. The method includes providing an electrosurgical probe such as those described immediately above, inserting the electrical surgical probe to a first position within tissue containing a target nerve and applying stimulation energy to an electrode. Upon the application of stimulation energy, a first response of a muscle associated with the target nerve may be observed. Thereupon, the electrosurgical probe may be moved to a second position and a second application of stimulation energy may be undertaken. The method further includes observing a second response of a muscle associated with the target nerve and comparing the second response with the first response. The method may also include varying the level of stimulation energy between the first and second applications of stimulation current. If the electrosurgical probe provided to implement the method has a third electrode, stimulation energy may be applied to a select third electrode as well. Certain advantages will be observed with respect to positioning the electrosurgical probe if stimulation energy is sequentially applied to first, second, third and subsequent electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 Bi-Polar Driver System.

FIG. 2 Schematic diagram of the bi-polar needle.

FIG. 2A Schematic diagram of the split bi-polar needle.

FIG. 3A Magnified side view of conical bi-polar probe.

FIG. 3B Magnified side view of hollow chisel bi-polar probe.

FIG. 3C Magnified side view of tapered conical bi-polar probe.

FIG. 3D Magnified side view of split conical bi-polar probe.

FIG. 4 Schematic diagram of the bi-polar driver system.

FIG. 5A Ablation Procedure without Auxiliary probe.

FIG. 5B Ablation Procedure with Auxiliary probe.

FIG. 6. Side view Hybrid bi-polar needle for nerve ablation.

FIG. 6A Side view Hybrid bi-polar needle for tumor ablation.

FIG. 7 Side view of auxiliary nerve probe.

FIG. 7A Side view of auxiliary dual-tipped nerve probe.

FIG. 8 Side view of guided ablation procedure with auxiliary nerve probe(s).

FIG. 9 Sample electro-surgery waveforms.

FIG. 10 Side view of visually guided ablation procedure.

FIGS. 11-11A Controller and probe data base structure.

FIG. 12 is a side view of a single axis electrosurgical probe having equal surface area electrodes.

FIG. 13 is a side view of a single axis electrosurgical probe having two electrodes of differing surface areas.

FIG. 14 is a side view of a single axis electrosurgical probe having two electrodes of differing surface areas.

FIG. 15 is a side view of a single axis electrosurgical probe having three electrodes.

FIG. 16 is a side view of a single axis electrosurgical probe having three electrodes and a curved handle portion.

FIG. 17 is a side view of a single axis electrosurgical probe having multiple electrodes transverse a nerve.

FIG. 18 is a side view of a single axis electrosurgical probe having multiple electrodes parallel to a nerve.

FIG. 19 is a side view of a single axis electrosurgical probe having multiple electrodes crossing a nerve at an angle.

Certain terms used herein are defined as follows:

Medical Terms

Corrugator supercili muscles—skeletal muscles of the forehead that produce brow depression and frowning.

Cepressor anguli oris—skeletal muscle of the corner of the mouth that produces depression of the corner of the mouth.

Depressor labii inferioris—skeletal muscle of the lower lip that causes the lip to evert and depress downward.

Dystonias—medical condition describing an aberrant contraction of a skeletal muscle which is involuntary.

Frontalis—skeletal muscle of the forehead that produces brow elevation or raising of the eyebrows.

Hyperhidrosis—condition of excessive sweat production.

Masseter—skeletal muscle of the jaw that produces jaw closure and clenching.

Mentalis—skeletal muscle of the lower lip and chin which stabilizes lower lip position.

Orbicularis oculio—skeletal muscle of the eyelid area responsible for eyelid closure.

Orbicularis ori—skeletal muscle of the mouth area responsible for closure and competency of the lips and mouth.

Parasymapathetic—refers to one division of the autonomic nervous system.

Platysma myoides—skeletal muscle of the neck that protects deeper structures of the neck.

Platysma—same as above.

Procerus muscles—skeletal muscle of the central forehead responsible for frowning and producing horizontal creasing along the nasofrontal area.

Procerus—same as above.

Rhinorrhea—excessive nasal mucous secretions.

Supercilli—a portion of the corrugator muscle that sits above the eyelids.

Temporalis—skeletal muscle of the jaw that stabilized the temporamandibular joint.

Zygomaticus major—skeletal muscle of the face that produces smiling or creasing of the midface.

Electrical Terms.

ADC: Analog to digital converter.

ASCII: American standard of computer information interchange.

BAUD: Serial communication data rate in bits per second.

BYTE: Digital data 8-bits in length.

CHARACTER: Symbol from the ASCII set.

CHECKSUM: Numerical sum of the data in a list.

CPU: Central processing unit.

EEPROM: Electronically erasable programmable read only memory.

FLASH MEMORY: Electrically alterable read only memory. (See EEPROM)

UI: Graphical user interface.

HEXADECIMAL: Base 16 representation of integer numbers.

12C BUS: Inter Integrated Circuit bus. Simple two-wire bidirectional serial bus developed by Philips for an independent communications path between embedded ICs on printed circuit boards and subsystems.

The I2C bus is used on and between system boards for internal system management and diagnostic functions.

INTERRUPT: Signal the computer to perform another task.

PC: Personal computer.

PWM: Pulse-width modulation.

ROM: Read only memory.

WORD: Digital data 16-bits in length

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates two main components and one optional component, which are the energy generator 400, the probe 371 (alternate probes are described in FIGS. 3A-D) and optionally probes 771 or 772 that may be used.

In normal operation, the novel probe 371 would combine a unique bipolar configuration in a single MIS needle, is inserted into the patient using MIS techniques. The probe, which may contain and/or convey various functions described later, is initially guided anatomically to the region of the anticipated or desired location. Various means of locating the tip 301 are utilized of placing the zone of ablation in the proper area to interrupt signal flows through the nerve 101.

Device Operation

Many combinations of electrode diameters and tip shapes are possible. The ‘novel’ probe performs a variety of functions, such as stimulation, optical and electronic guidance, medication delivery, sample extraction, and controlled ablation. This bi-polar electrode is designed as a small diameter needle inserted from a single point of entry thus minimizing scaring and simplifying precise electrode placement. This low cost, compact design provides a new tool to the art.

Probes may emit fiber optic illumination for deep applications using electronic guidance as taught in FIGS. 1 and 8. The invention offers a simple low cost ablation probe that is capable of performing precise ablation while minimizing damage to nearby tissue structures. The metered ablation energy and precise probe targeting give the practitioner a tool is also not available in prior art. The practitioner has unprecedented control of treatment permanence in a minimally invasive procedure. Such a procedure is typically performed in less than one hour with only local anesthetic and would require no stitches or chemicals common to prior medical art.

Stimulation/Ablation

First the probe electrode 301 must be in the desired location relative to the target nerve 101 (FIG. 4), then the user initiates the treatment via switch(s) 410 and 310 using the selected power setting 404 (FIG. 4). The controller configures the generators 411 (FIG. 4) and 412 to the amplitude frequency and modulation envelope, delivering 50 KHz-2.5 MHz of 5 to 500 watts of available energy. The summing junction 413 combines the RF outputs as the application requires and passes them to the pulse-width modulator 415 for output power control. The output of modulation generator 420 is applied to the multiplier 415 with radio frequency RF signals 422 and 423. This permits complex energy profiles to be delivered to a time variant non-linear biologic load. All of these settings are based on the information provide to the generator by the installed probe 371 the selected power 404 settings, and the modulation envelope 420 (FIG. 4) settings, which are then loaded by the generator 421.

For example, both a high amplitude sine wave 910 (FIG. 9), used for cutting, and a pulse-width modulated (or PWM) sine wave 920, used for coagulation, are well known to electro-surgery art. Precise power rates and limits of average total power are controlled via integrator 435 minimizing damage to nearby structures or burning close to the skin for shallow procedures. Where nearby structures 111(FIG. 2A) are too close to be avoided by electrodes such as 371 (FIG. 3), 372 (FIG. 3A), and 372 (FIG. 3B), additional probe geometries as taught in FIGS. 3D, 6 and 6A offer novel methods to direct energy and limit ablation to a smaller region, thereby avoiding other structures. For safety a hardwired switch 436 disables the power amplifier in the event of a system fault, the probe is unplugged or over power condition, thus protecting both the patient and practitioner.

The output of the modulator 415 is applied to the input of the power amplifier 416 section. The power amplifier's 416 outputs are then feed into the impedance matching network 418, which provides dynamic controlled output to the biologic loads that are highly variable and non-linear, and require dynamic control of both power levels and impedance matching. The tuning of the matching network 418 is performed for optimal power transfer for the probe, power level, and treatment frequencies settled. The system's peak power is 500 watts for this disclosed embodiment. Precise control is established by the proximity of the tip and the control loops included in the generator itself The final energy envelope 420 is delivered to probe tip 301 and return electrodes 302.

This precise control of energy permits extension of the ablation region(s), 140 and 1203 (FIG. 10), and the duration of treatment efficiency. Low or medium energy settings 404 permit temporary nerve-conduction interruption for 3-6 months. Higher energy settings at 404 may result in a longer nerve conduction interruption of 1 year to permanent. In the prior art, procedures had little control over duration of termination of such signal flow through the nerve. This invention gives the practitioner enhanced control of such duration. Patients can evaluate controlled temporary treatment before choosing longer or permanent treatment options.

A low energy nerve stimulator 771 has been integrated into the system to assist in more precise identification of nearby structures and for highly accurate target location. Lastly, additional sensors, such as temperature 311, voltage, frequency, current and the like are read directly from the device and/or across the communications media 403 to the probe.

Directed Ablation

In addition to the substantial radially-symmetric ablation patterns with probes as taught in 371 (FIG. 3) and 372, switching or dividing ablation power to multiple electrodes (FIG. 3D) can generate an asymmetric ablation zone. This high intensity source 608 with probe 610 (FIGS. 6 and 6A) minimizes damage to nearby structures 111 or the burning of skin 330 in shallow procedures. Also, FIGS. 2A and 3D identify probe configurations for selective or asymmetric ablation.

Power Feedback

The power amplifier output430 and buffered the feedback signals 437 are connected to an Analog to Digital converter (or ADC) 431 for processor analysis and control. Said signals 437 control power modulation 420 settings and impact the impedance matching control signals 419. This integrated power signal 437 is recorded to the operating-condition database (FIG. 11) for later procedure review. This power level is also compared to reading taken from the probe 1492 (FIG. 11A) as compared against procedure maximums, which if exceeded will in turn disable the amplifier output, thereby protecting the patient from error or equipment fault. Similarly, limits from the probe and generator sensors such as temperature 330 are also used to terminate or substantially reduce the modulated power levels and ultimately the procedure.

Probe Identification

At power startup, the controller 401(FIG. 4) reads the probe status and internal identification kept within the probe itself 331 (and 371) via serial communications 403 (or bus). Serial communications is used because it is commonly available to most single-chip microprocessors. This or similar methods (e.g. I2C, or SPI) may be used, but this disclosed embodiment will use serial for its simplicity. Serial communications 403 permits the generator to address and control EEROM memory 331, temperature sensors 330, processors, ADC and DACs within the single-chip microprocessor embedded in the probe itself The user selects the desired power setting 404 and based on probe identification read from the EEROM or microprocessor 331 makes the appropriate configurations. The probe 371 is connected via cable 1334 (FIG. 1) to control unit 101 or generator. This probe is not intended for multiple procedural uses. So to prevent such use of the probe, the controller 401 (FIG. 4) reads the stored time register from ID memory module 331. If the probe's initialized time 1467 (FIG. 14) is zero, the current real-time clock 482 value is written to probe's 331's initial time register via serial bus 403. If time read on module 331 is non-zero, the probe's initial time register is added to two(2) times the procedural time (based on the probe type) FIG. 14 1420. If that value when compared to current real-time clock 482, is less than current time, the controller will alert the practitioner via display 450, speaker 451 and, flashing probe illumination 608, that the procedure will be terminated and the probe rendered invalid.

The controller 401 also verifies selected procedure 1415 (FIG. 11) for compatibility with installed probe. If incompatible, the user is also prompted to select a different power setting 404, procedure, or probe 371. If probe 371 matches power setting 404, the system enables power amplifier 416, guide light source 408, and low-voltage nerve simulation 732. Both of these procedures are enforced by a mandatory “hand shake” protocol and the serialized information, which must be present and properly verified by the electronic circuitry for a procedure to be instituted. During a clinical procedure, information is required to be conveyed by the embedded electronics contained within the probe, which provides another way of enforcing this protection and thus again preventing unauthorized re-use. The ultimate goal is prevent cross-contamination between patients. The probe will accomplish this by being unique, serialized, and given the above procedures. Once plugged in, the probe will enter the serial number into the data logging system via the serial bus 403 and circuit logic will thereafter prevent re-use of the probe and cross-contamination that would occur. Further, this scheme will prevent the use of unauthorized third party probes, for they will not be activated, preventing potential inferior or uncertified probes from being used and presenting potential danger to the patient.

Nerve Target Location Tools

Prior to treatment, the practitioner may use auxiliary probe 771(FIG. 4), to locate target 101 and nearby structures 111 as taught in FIGS. 4, 7, 7A, 8, and 10. When needle 771 is in place, the practitioner may locate and place a mark or marks on the surface of the skin 755 (see FIGS. 7 and 8) or leaves auxiliary probe 771 in place. For shallow sub-cutaneous procedures, probe tip illumination 448 from source 408 is visible to practitioner aiding in probe placement to pre-marked location.

Location Via Florescence Marker Dye.

In other procedures, whereby somewhat larger targets are sought, such as more diffuse nerve structures or small areas of abnormal growth (e.g. such as cancer) the injection of specially designed dyes that attach to target structures are used, as taught in FIG. 6A. The probe 610 (FIG. 6) is moved into the proximity of the target 671. The light source 608 illuminates quantum-dot/dye tagged antibody 670. The dye fluoresces 675 at a frequency/wavelength of a particular material and will typically emit light in the visible to infrared (or IR) or potentially other wavelength regions. The return fiber(s) 680 deliver emissions 675 to the detector 478 for measurement and are the result is then displayed on bar graph 554 (FIG. 1) and/or an audio tone sounded via speaker 451 based on proximity. Visible and IR light emissions propagate over limited distances permitting additional external detectors 678 to be used for shallow targets just under the skin 330. Location via this method is similar to the electronically guided probe method taught in FIG. 8 where probe 610 movement maximizes the signal output when in close proximity. IR emissions propagate and can permit deeper (typically several centimeters) detection with optional additional external sensors 678. Unfortunately, many dyes fluoresce in the visible region making external detection imposable for deep targets or when obscured by bone. However, probe 610 (FIG. 6A) solves this problem by integrating target illumination 674, emission 675 detector, ablation, biopsy, and medication delivery in single compact probe. Electronic probe guidance (FIG. 8) if required is used in combination with florescence detection to rapidly locate target. The instant invention offers a minimally invasive system for locating and treating small/deep tumors and other tissue that are to be ablated, destroyed or removed.

Electronic Probe Guidance

Low energy nerve stimulation current 810 (FIG. 8) assist in locating desired treatment region and avoiding nearby structures. Probe 771 is selectable between nerve stimulator and current measurement to/from auxiliary probe tip 702(FIG. 8). Return electrode 736 provides a return path for local ground 735. Ablation probe switch 367 selects low-energy stimulator/receiver and high-energy ablation to/from probe 372. Amplitude of measured guidance current 811 and light 478 are transmitted to display 554, and audio feedback 452 through the speaker 451.

Optical Probe Guidance

Disclosed invention provides optical sources 408 that aid in probe placement (FIG. 10) by supplementing stimulation source 732 and acting as preliminary guide. Probe 771 is selectable between nerve stimulator or current 811 measurement and to or from the auxiliary probe tip 702. The ablation probe switch 367 selects low-energy stimulator/receiver or high-energy ablation to or from probe 371, 372, 373, and 374. In this mode, the physician operator will have previously placed marks 755 on the surface of the skin by various means described. The physician operator 775 will then see the tip when the 448 if the optical illumination is turned on. It 448 will provide a bright spot under the skin indicating the location of the tip in relation to the marks 755. The physician 775 will then guide the probe tip 301 into precise alignment under these marks 755 so as to enable ablation of that target tissue 101.

Data and Voice

Real-time engineering parameters are measured such as average power 437, luminous intensity 478, probe current 811, energy 438 and, temperature 330 to be recoded into USB memory 438. Simultaneously, the internal parameters disclosed such as frequency 423, modulation 420 and such are recoded into USB memory 438 as well. Additionally probe, patient, and procedure parameters (FIG. 11) are written to local storage 438. The practitioner dictates text and voice notes via microphone 455, which are saved to memory 438 (FIG. 1). All data and records are time stamped using the real-time clock 482. This permits detailed post procedure graphing and analysis.

Data Transfer

At procedure conclusion, the system transfers the data 438 recorded to the USB removable memory 1338 and to a file server(s) 1309 and 1307. In the disclosed embodiment, data transfer is performed over Ethernet connection 480. Probe usage records 1460(FIG. 11) that are stored in local memory 438 are then written to removable memory module 1338. Parallel records are mirrored to local storage 1309 and remote server 1306 storage 1307 via Ethernet connection 480 or similar means. Sensitive records are encrypted and transferred via secure network connection and also written to removable module 1320. The database contained on the remote server tracks the following information: equipment by manufacture, probe accessory inventory, usage, billing, repair/warranty exchange information, and program recorders. As a system 400 is certified for new procedures 1410 (FIG. 11), the relational databases are automatically updated to reflect new billing/procedure codes 1416, potential power settings 1417 and the like. This insures that the equipment is current and alerts the practitioner to new probes/procedures as they are developed and certified.

Before further explaining the disclosed embodiment of the present invention in detail, it is to be understood that the invention is not limited in its application or to the details of the particular arrangement shown. The invention is capable of other embodiments. Further, the terminology used herein is for the purpose of describing the probe and its operation. Each apparatus embodiment described herein has numerous equivalents.

FIG. 1 Bi-Polar Driver System

FIG. 1 identifies the two required components of the system, various modules and optional items. The two components always utilized during a procedure will be the energy generator/controller/data storage device 400 and probe 371. 400 contains advanced electronic systems capable of recognizing a properly authorized probe, preventing re use of a previously used probe, generating appropriate energy as described, performing safety checks, storing data, and other functions as described. Main functions of 400 may include, but not be limited to, generation of light, generation of location-stimulation currents, generation of ablation energies, data logging, storage, communication and retrieval, and other functions critical to a MIS procedure. Probe 371 and its various forms are single puncture bipolar surgical tools that may be used in identifying proper location of its tip 301, in relation to target tissue 101 which is desired to be ablated, modified or destroyed. Probe 771 and its various derivatives may optionally be used to assist in locating and properly positioning tip 301 of probe 371.

FIG. 2 Isometric View of the Bi-Polar Probe

Bi-polar probe 310 represents probes 371, 372, 373 shown in FIGS. 3A-C with exception to type of needlepoint on the probe. FIG. 3D varies from the other because it has a split return probe. Bi-polar probe 310 (not drawn to scale) consists of insulating dielectric body 309 made from a suitable biology inert material, such as Teflon, PTFE or other insulative material, covering electrode 302 except for where 302 is exposed as a return electrode. Conductive return electrode 302 tube is fabricated from medical grade stainless steel, titanium or other conductive material. Hollow or solid conductive tip electrode 301 protrudes from surrounding dielectric insulator 305. Sizes of 309, 302, 305, and 301 and its inner lumen (diameter, length, thickness, etc.) may be adjusted so as to allow for different surface areas resulting in specific current densities as required for specific therapeutic applications.

Hollow Electrode 301 often used as a syringe to deliver medication such as local anesthetic. Tip electrode 301 is connected to power amplifier 416 via impedance matching network 418 (FIG. 4). Return electrode(s) 302 delivers return current to power amplifier 416 via impedance matching network 418. Dielectric insulator in the disclosed embodiment is a transparent medical grade polycarbonate acting as a light pipe or fiber optic cable. Light source LED or laser 408 (FIG. 4) provides illumination at the far end of the probe via fiber optic cable/transparent dielectric 305 for guiding the probe under the skin i.e. shallow procedures. In an alternate embodiment dielectric insulator is replaced with a plurality of optical fibers for viewing and illumination as taught in FIG. 6.

Ablation regions 306 and 140 extend radially about electrode 301 generally following electric field lines. For procedures very close to skin 330 a chance of burning exists in region 306. To minimize the chance of burning, a split return electrode probe 374 in FIG. 3D is offered. Thereby concentrating the current away from region 306 to 140 or vice versa. In FIG. 2A, insulator 307 splits the return electrode into two sections 302 and 303, dividing return current ratio from 0-50%, which may also be selectively activated. Active electrodes are also split into two sections 301 and 311 so energy may be directed in a desired direction. This electrode configuration is identified on the proximal portion of the probe so the operator may position the needle and electrodes accordingly. FIG. 6 teaches a laser directed ablation for more precise energy delivery.

FIG. 2A Isometric View of Split Bi-Polar Probe.

The bi-polar probe 380 (not drawn to scale) consists of an insulating dielectric body 309 made from a suitable biologically inert material, such as Teflon PTFE or other electrical insulation, that covers split return electrodes 302 and 303. The disclosed conductive return electrodes 302 and 303 are fabricated from medical grade stainless steel, titanium or other electrically conductive material. Hollow or solid split conductive tip electrodes 301 and 311 protrude from the surrounding dielectric insulator 305. The operation of the hollow/split conductive tip is very similar to probe tip 310 as taught in FIG. 3D. Ablation regions 1203 (FIG. 10) and 140-144 extend radially about electrode 301 generally following electric field lines. For procedures very close to skin 330 a chance of burning exists in region 306. To minimize chance of burning a split return electrode probe 311 is used, thereby concentrating the current away from region 306 to 140. For procedures where there is a risk to nearby structures 111, the ablation region 1203 must be a non-radial ablation zone. The disclosed split electrode 380 permits dividing or splitting energy delivered to electrode pairs 301/302 and 311/303. The disclosed division or ratio between pairs is 0-100%. Dual amplifiers or time multiplexing/switching main amplifier, 416 located between electrode pairs, directs energy to target 101 avoiding 111. This simple switch network reliably ratios electrical energy while minimizing damage to nearby structures.

FIG. 3A Conical Bi-Polar Needle

Bi-polar probe 371 discloses conical shaped electrode 301 and tip 351 for minimally invasive single point entry. Probe diameter 358 is similar to a 20-gage or other small gauge syringe needle, but may be larger or smaller depending on the application, surface area required and depth of penetration necessary. In disclosed embodiment, electrode shaft 302 is 30 mm long with approximately 5 mm not insulated. Lengths and surface areas of both may be modified to meet various applications such as in cosmetic surgery or in elimination of back pain. The conductive return electrode 302 is fabricated from medical grade stainless steel, titanium or other conductive material. The dielectric insulator 305 in the disclosed embodiment is a transparent medical grade material such as polycarbonate, which may double as a light pipe or fiber optic cable. The high intensity light source 408 LED/laser (FIG. 4) provides guidance Illumination 448 at working end of probe. The illumination source modulation/flash rate is proportional to the received stimulation current 810 as taught in FIG. 8. A small diameter electrode permits a minimally invasive procedure that is typically performed with local anesthetic. This configuration may contain lumens for delivery of agents as described elsewhere.

FIG. 3B Hollow Chisel.

The hollow chisel electrode 352 is often used as a syringe to deliver medication such as local anesthetic, medications,/tracer dye. The hollow electrode may also extract a sample. Dielectric insulator 305 in the disclosed embodiment is a transparent medical grade polycarbonate and performs as a light pipe or fiber optic cable. The novel dual-purpose dielectric reduces probe diameter and manufacturing costs. Light source 408, typically a LED or laser (FIG. 4 not shown), provides Illumination 448 at the working end of probe. It provides an illumination source for guiding the probe under the skin. A second embodiment, as taught in FIG. 6, dielectric insulator is replaced/combined with plurality of optical fibers for viewing/illumination.

FIG. 3C Tapered Conical

The bi-polar probe 373 discloses a tapered conical shaped probe for minimally invasive single point entry. It is constructed similarly to probe 371 as taught in FIG. 3A. Probe tip is not drawn to scale to teach the tip geometry. In disclosed embodiment, electrode 301 is approximately 5 mm long and fabricated from medical grade stainless steel but may be of various lengths to accommodate specific application and surface area requirements. The solid tapered conductive tip electrode 353 protrudes from tapered dielectric insulator 305. Transparent dielectric insulator 305 also performs as light pipe or fiber optic cable terminated to high intensity light source 408 (FIG. 4) providing illumination 448. The electrode assembly is mounted in an ergonomic handle 388 (which has not been drawn to scale). Handle 388 holds ablation on/off switch 310, ablation/stimulation mode switch 367, identification module 331 and terminations for cable 1334 (FIG. 13). Temperature sensor 330 (located close to tip) monitors tissue temperature.

FIG. 3D Split Conical Bi-Polar Probe

Description of this probe is described in both drawings 2A and 3D. Bi-polar probe 374 (not drawn to scale) consists of insulating dielectric body 309 made from a suitable biologically inert material, such as Teflon, that covers split return electrodes 302 and 303. Conductive return electrodes 302 are fabricated from medical grade stainless steel, titanium or other suitable conductive material. Hollow or solid split conductive tip electrodes 301 and 311 protrude from surrounding dielectric insulator 305. Their operation is very similar to probe tip 380 as taught in FIG. 2A. Solid tapered conductive tip electrodes 311 and 301 protrude from transparent dielectric insulator 305. Dielectric insulator 305 also performs as a light pipe or fiber optic cable terminated to high intensity light source 408 providing illumination 448.

Probe handle (not drawn to scale) encloses memory module 331, on/off switch 310 and mode switch 367. Temperature sensor 330 (located close to tip) monitors tissue temperature. Split electrode 380 (FIG. 2A) permits dividing or splitting energy delivered to electrode pairs 301/302 and 311/303. Dual amplifiers or time multiplexing/switching main amplifier 416 are located between electrode pairs directing energy to target 101 avoiding 111 creating asymmetric ablation volume. A small diameter electrode needle is injected from a single point of entry minimizing scaring and simplifying precise electrode placement.

Connections consist of a tapered dielectric sleeve 309 covering the ridged stainless electrode tube 302. Insulating sleeve 309 is made from a suitable biologically inert material, which covers electrode 302. Dielectric 305 insulates conical tipped electrodes 351 and 301.

FIG. 5A Ablation Procedure (Without Auxiliary Probes)

Ablation probe 371 is inserted and directed anatomically into the area where the target nerve to be ablated (Box 531) is located. Test current 811 is applied (Box 532). If probe is located in the immediate proximity of the target nerve a physiological reaction will be detected/observed (Example: During elimination of glabellar furrowing, muscle stimulation of the forehead will be observed). If reaction is observed, then a mark may optionally be applied on the surface of the skin to locate the area of the nerve. Power is applied (Box 535) in an attempt to ablate the nerve. If physiological reaction is not observed, (Box 534) the probe will be relocated closer to the target nerve and the stimulation test will be repeated (Box 536 & 537). If no physiological reaction is observed, the procedure may be terminated (Box 544). Also, the probe may be moved in any direction, up, down, near, far, circular, in a pattern, etc. to create a larger area of ablation for a more permanent result.

In Box 537, if stimulation is observed again, then the ablation power may be set higher (Box 538), alternatively, as mentioned, the needle may be moved in various directions, or a larger dosage of energy may be reapplied, to form a larger area of ablation for more effective or permanent termination of signal conduction through the nerve. After delivery of power (Box 540), stimulation energy may be applied again (Box 541). If there is no stimulation, the procedure is completed (Box 544). If there is still signal flow through the nerve (stimulation or physiological reaction) then the probe may be relocated (Box 542) and the procedure is started over again (Box 533).

FIG. 5B Flow Chart of Visually Guided Ablation Procedure Using Auxiliary Probes Such As 771 and 772.

Auxiliary probes 771 and 772 (FIGS. 7 and 7A) provide a method to quickly and accurately locate target structure 101 and subsequently mark target location 755. Auxiliary probes may be much smaller (like acupuncture needles) than ablation probes. Structures are marked typically with an ink or similar pen allowing the illuminated ablation probe 371 or other ablation probe to be quickly guided to mark 755. Optionally, non-illuminated probes may be used allowing the practitioner to simply feel for the probe tip. For deep structures, probe 771(FIG. 8) us employed as an electronic beacon. Small current 811, which is similar to the stimulation current but smaller, from probe tip 702 is used to guide ablation probe 372 (FIG. 8).

Operation 530 (FIG.5B) inserts auxiliary probe 771 or 772 (FIGS. 7 and 7A) thru skin 330 and muscle layer(s) 710 near nerve 101. Target 101 depth 766 is measured (FIGS. 7 and 7A) using auxiliary probe markings 765. Decision 533 checks if the probe is in position if not adjustments are performed in 534. Operation 532 enables nerve simulation current 811. When muscle stimulation is obtained or physiological reaction is obtained, Auxiliary probe tip is in place. Depth may be noted by reading marks 765 and location marks 755 may be made in operation 535. With the probe in position under mark in operations 536 and 537, operation 538 sets power level 404 and closes ablation switch 410. Alternatively, stimulation may be applied directly from the ablation probe as taught elsewhere. Operation 540 and controller 401 set generator 411 (FIG. 4) frequencies, modulation 420 envelope and enables power amplifier 416 to deliver preset ablation energy. Region 1203 (FIG. 10) shows the general shape of the ablation region for conical tip 301 for example.

Between each ablation, procedure 540 (FIG. 5C) (nerve conduction) is tested in 541. Probe amplifier 416 delivers small nerve stimulation current 811 from electrode 301 or Auxiliary probe 771 or both. Based on the nerve conduction test 541 if the desired level of conduction is achieved the procedure is compete. Operation 542 moves the probe to the next position and repeats conduction test 541. If compete, the probe(s) is removed in operation 544. Number and ablation intensity/energy are set by the particular procedure and the desired permanence. The practitioner selects the procedure/power level 404 (FIG. 4) and controller 401 compares the installed probe via identification 331 (FIG. 4) for compatibility with selected procedure. The practitioner is alerted if the installed probe is incompatible with selected power range 404.

As an example and not a limitation, five ablation regions (140, 141, 142, 143, and 144) are shown in FIG. 10. Ablation starts with area 144, then the probe is moved to 143 and so on to 140. Alternatively, movement may be during insertion, moved laterally, in a circular manner or other manner to enlarge the area of targeted nerve destruction. Nerve responses may be tested after each ablation allowing the practitioner to immediately check the level of nerve conduction. Probe position and power adjustments are made before applying additional ablations if required. Accurate probe location tools and methods taught herein permit use of minimal ablation energy thereby minimizing damage to non-target structures. This translates to reduced healing time and minimal patient discomfort. The instant invention gives the practitioner a new tool to perform a minimally invasive nerve conduction limiting procedure with the ability to select, temporary or permanent nerve conduction interruption with a new level of confidence. This new tool offers a low cost procedure performed typically in office or outpatient setting often taking less than one hour with local anesthetic. In contrast to prior art where surgical procedures require stitches and longer healing intervals with limited control of permanence (nerve re-growth).

FIG. 6 Side View of the Bi-Polar Probe 610 With Enhanced Laser Targeting.

Probe insertion and placement is same as taught in FIG. 3. Probe construction is the same as FIG. 3 with the dielectric 305 having embedded optical fibers 690 and 680 providing imaging/illumination. Additional fiber(s) 690-691 are illuminated by a high intensity laser source.

In special cases were target nerve 101 or ablation region 640 is in close proximity to second nerve 111 or skin 330 bi-polar probes 371 or 372 (FIG. 3) create an annular ablation region between electrodes 301 and/or 302, potentially damaging nearby structures such as other nerves 111. With probe 610 in the desired position, laser 608 (FIG. 4) is turned on target 670 (FIG. 6A) with illuminating fiber(s) 690. Fiber(s) transmitting high intensity laser light to ionized region 640 is illuminated by fiber(s) 690. Simultaneous with laser illumination, RF energy 470 is delivered to electrodes 301 and 302. A relatively low impedance path is created by the high intensity laser illumination wherein RF energy will follow this newly created path. Thus very specific regions may be selected for ablation. By permitting operation at a lower power, energy is concentrated where it is needed and eliminates or reduces damage to nearby structures such as skin 330 or nerves 111. Probe 610 improves on the already very precise ablation taught in FIG. 3 with the addition of a low power laser (or other type light source) and fiber delivery system. In the disclosed embodiment a diode pumped Nd:YAG (Neodymium Doped Yttrium Aluminum Garnet) laser is offered as an example and not a limitation.

FIG. 6A Side View is the Florescence Emission Guided Hybrid Bi-Polar Tumor Probe.

Probe construction is similar to FIGS. 3A and 6 with dielectric 305 embedded with a plurality of optical fibers 380, 690, and 680 for illumination detection/imaging. These enhanced systems and processed augments the selective nature of previously disclosed probes. Fiber(s) 690-691 are illuminated by a high intensity light source(s) 608 which is typically a tunable laser or UV LED. Source(s) 608 (FIG. 4) provides illumination for tagged marker(s) 670 in the disclose embodiment where a tunable laser is employed. Excitation/illumination wavelength(s) are specific to the dye/nano-particle used with marker 670 that is very specific for the desired target 671. The marker/tag is typically a protein specific antigen combined with a florescent marker. The novel probe illumination permits delivery of intense illumination to the target for maximum system sensitivity. Many dyes excited by short (Blue/UV) wavelength light are transmitted poorly in tissue but are easily delivered by fiber 690. A second application offered for hybrid bi-polar ablation probe 610 is for locating/destroying small cancer lesions. The probe addresses cases where surgery is not practical or it dangerous due to location or sub-operable size. Quantum-dot or dye tagged antibody materials 670 are injected into the patients where it attaches to target structure 671. Once tagged, cancer node(s) may be located, tested, and treated.

FIG. 7 Side View of Auxiliary Single Tipped Nerve Probe

This probe may be used in conjunction with any of the therapeutic probes 371 and their derivatives. The needle itself will be very fine in nature, such as an acupuncture type needle. By its small size, numerous needle insertions may be accomplished with no scarring and minimal pain. The probe 771 will be inserted in the vicinity of the target tissue through skin 330. The exposed tip of 771, 702 will be exposed and electrically connected to generator 732 via wire 734. The surface of probe 771 is covered with dielectric 704 so the only exposed electrical contact is surface 702 and return electrode 736. Exposed tip 702 will be advanced to the vicinity of target 101 and test stimulation current will be applied. Appropriate physiological reaction will be observed and when the tip 702 is properly located, depth will be noted via observing marks 765. External mark 755 may be applied for reference. Ablation probe 371 may then be advanced to the proximity of the target tissue under the X mark 755 and ablation/nerve destruction as described elsewhere may be performed.

FIG. 7A Side View of Auxiliary Dual-Tipped Nerve Probe.

Dual tipped probe 772 offers an additional embodiment that eliminates return electrode pad 736. Probe frame/handle 739 holds two fine needles, 702 and 701, in the disclosed embodiment that are spaced a short distance (a few mm)-mm apart (730). The shaft of conductive needle 701 is covered with dielectric insulator 706, similar to the construction of probe 771 (FIG. 7). The shaft of the second conductive needle 702 is covered with dielectric insulator sleeve 703. Electric generator 732 provides current to the probes via conductors 734 and 735. Current originates from 701 and returns via electrode 702. Large probe handle 739 is drawn out to teach the dual probes. To aide in probe depth measurement, markers 765 are printed on needle shafts. Dielectric insulating sleeves 703 and 706 isolate the needle shaft current from muscle layer 710. Current applied via generator 732 stimulates the nerve directly while avoiding muscle 710. Smaller probe tips with smaller current permits accurately locating small structures.

Probes 702 and 701 are very small gage needles similar in size to common acupuncture needles, thus permitting repeated probing with minimal discomfort, bleeding, and insertion force. Sharp probes are inserted thru skin 330 and muscle layer(s) 710 near nerve 101. The practitioner locates target nerve 101, then the skin surface may be marked 755 as location aide for ablation step as shown in flow chart (FIG. 5B). Once the desired site of ablation is located, ablation probe(s) 610(FIG. 6), 371 and related probes (FIG. 3), may be inserted under skin 330, illuminated 448 by tip 305. They are visible through skin (via illumination 448 from tip 305) and are guided to mark 755 (FIG. 8). The observed intensity 765 from illumination source 305 is used as an estimator of measured depth 765. This simple probe system permits rapid, accurate locating of target structures with minimal pain and injury. Accurate target location permits use of lower ablation energy thereby minimizing damage to nearby structures.

FIG. 8 Side View of Guided Ablation Procedure With Auxiliary Nerve Probe(s).

Auxiliary probes 771 and 772 (FIGS. 7 and 7A) are used to accurately locate target structure 101. Probe 771 holds a fine conductive needle 702 that has a shaft covered with dielectric insulator 704. Electric generator 732 provides a small current to the auxiliary probe via conductor 734 and return conductor 735 via return electrode 736. The sharp auxiliary probe is inserted thru skin 330 and muscle layer(s) 710 near target nerve 101. Dielectric insulating sleeve 704 isolates needle shaft from muscle layer 710. Current is applied via generator 732 thereby stimulating the nerve directly while avoiding muscles 710. Prior art probes without insulating sleeve 704 stimulate both the nerve and muscle simultaneously, masking nerve 101 and subsequently making nerve location difficult.

Auxiliary probe 771 and 772 provide a method to quickly locate shallow or deep target structures. Shallow structures are typically marked with ink pen allowing illuminated ablation probe 371 or its equivalents to be quickly guided to mark 755. Optionally, non-illuminated probes may be used by the practitioner who simply feels for the probe tip. For deep structures, probe 771 may also be employed as an electronic beacon; small current 811 (which will be lower intensity and different from the stimulating current) from probe tip 702 is used to guide ablation probe 372. Amplifier 430 (FIG. 4) detects current from tip electrode 301 for reading and displays it by controller 401. Alternately probe 701 is used as a receiver detecting current 811 from electrode 301 Moving probe tip 301 horizontally 1202 and in depth 766 relative to auxiliary probe 702 changes current 810 inversely proportional to distance. Detected signal current 811 isolated and buffered by amplifier 430, is measured and the current is displayed to simple bar graph 554 for rapid reading. In addition, audio feedback, in which the tone is modulated by proximity of probe tip 351, 352 or equivalent in relation to auxiliary probe tip 702 is provided to minimize or eliminate the practitioner having to look away from the needle, thus assisting in accurate probe placement. Variable frequency/pitch and volume audio signal are proportional to sensed current 811 that is generated by 452. The tone signal emitted by speaker 451 (FIGS. 4 and 1) provides a pleasant and accurate method to aide in probe placement. Simultaneously, illumination source 408 is modulated by amplifier 456 to blink at a rate proportional to the sensed current. This permits the practitioner to quickly and accuracy guide ablation probe 372 into position using a combination of audio and visual guides. The audio and visual aides also reduce the practitioner's training/learning time. The novel real-time probe placement feedback gives the practitioner confidence that the system is working correctly so he/she can concentrate on the delicate procedure. Accurate probe location permits use of minimal energy during ablation, minimizing damage to non-target structures and reducing healing time and patient discomfort.

FIG. 9 A High-Energy Electro-Surgery Sinusoid Cutting Waveform 910.

Lower energy pulse width modulated (or PWM) sinusoid 920 for coagulation is also well known to electro-surgery art. Variations of cut followed by coagulation are also well known.

FIG. 10 Side View of Visually Guided Ablation Procedure.

Auxiliary probes 771 and 772 (FIGS. 7 and 7A) have accurately located target structure 101 and subsequently marked target locations 140 to 144. Shallow structures are marked typically with ink pen (755) allowing illuminated ablation probe 371, 372 or equivalent to be quickly guided to that point. For deep structures, probe 771 is employed as electronic beacon, small current 811 from probe tip 702 is used to guide ablation probe 372 as taught in FIG. 8.

Ablation probe 372 is inserted thru skin 330 and muscle layer(s) 710 near nerve 101. Illumination source 408 permits practitioner to quickly and accuracy guide illuminated 448 ablation probe 372 into position. Illumination 448 from ablation probe as seen by practitioner 775 is used as an additional aide in depth estimation. Selectable nerve simulation current 811 aids nerve 101 location within region 1204. This novel probe placement system gives practitioner confidence system is working correctly so s/he can concentrate on the delicate procedure. Accurate probe location permits use of minimal energy during ablation, minimizing damage to non-target structures and reducing healing time and patient discomfort.

Region 1203 shows the general shape of the ablation region for conical tip 301. Tip 301 is positioned in close proximity to target nerve 101. Ablation generally requires one or a series of localized ablations. Number and ablation intensity/energy are set by the particular procedure and the desired permanence.

Five ablation regions are illustrated 140, 141, 142, 143, and 144; however, there could be more or less regions. Ablation starts with area 144, then the probe is moved to 143 and so on to 140, conversely, ablations could start at 140 and progress to 144. Also, the practitioner could perform rotating motions, thus further increasing the areas of ablation and permanence of the procedure. Between each ablation procedure 540 (FIG. 5C), a small nerve stimulation test current 811 is emitted from electrode 301. The approximate effective range of the nerve stimulation current 811 is shown by 1204. Testing nerve response after each ablation allows the practitioner to immediately check level of nerve conduction. Without probe 372 removal, the practitioner receives immediate feedback as to the quality of the ablation. Then minor probe position adjustments are made before conducting additional ablations (if required).

FIG. 11-11A Controller and Probe Data Base Structure

Controller 101 maintains local probe 1460, patient 1430, and procedure 1410 databases. All work together to insure correct probes and settings are used for the desired procedure. Automatically verifying that the attached probe matches selected procedure and verifying probe authentication and usage to avoid patient cross contamination or use of unauthorized probes. Automatic probe inventory control quickly and accurately transfers procedure results to the billing system.

FIG. 11—Procedure Parameters Code(s) Database 1410

From a touch screen, the practitioner selects the desired procedure from list 1410. For example “TEMPORARY NERVE CONDUCTION” 1411, “SMALL TUMOR 1CC” 1412, and “SMALL NERVE ABLATE” 1413 are a few of the choices. Each procedure has a unique procedure code 1416 to be used in the billing system. Power range parameter 1417 is a recommended power setting via power level control 404. The recommended probe(s) Associated with procedure 1415 and power range parameter 1417 are listed in parameters 1419. With the probe connected, the part number is read from memory 331 (FIGS. 1, 3 and 4) and compared to list 1419. The total power parameter 1418 is the maximum energy that the system may deliver for this procedure and is determined by the procedure code, probe being used and software parameters. These parameters may be modified, updated and changed as required by addition of new probes and procedures allowed/approved. Power is delivered, measured and totaled with integrator 435 (FIG. 4). The power integration circuit is designed as a hardwired redundant safety circuit that turns off the power amplifier if maximum energy is exceeded. This novel feature protects patients from system fault or practitioner error. Standard procedure time 1420 is doubled and added to current RTC 482 then written to probe memory 331 (in FIG. 1).

FIG. 11 & 11A—Probe Usage Authorization Database 1460

From touch screen 450 (FIGS. 1 and 4) practitioner selects desired procedure from list 1410. Probe 371 and equivalents (FIGS. 3A-D) type is selected from recommended list 1419 and is connected via cable 1334 (FIG. 1) to control unit 101. Once connected, controller 401 (FIG. 4) reads the stored time register from ID memory module 331 (FIG. 1). If start time 1487 read is zero (factory default), current real time clock 482 (FIG. 4) is written to database 1460 in the start time field 1467, 1430 and 1435. Simultaneously, twice the standard procedure time 1420 parameter is added to RTC 482 and written to time register 1487 via serial bus 403. If probe start time 1487 reads (331) non-zero, the value compared to real time clock 482. If greater than current time plus twice the standard selected procedure duration 1420, the controller alerts the practitioner via display 450, speaker 451 and flashing probe illumination 608 of previously probe used condition. To correct the situation, the practitioner simply connects a new sterile probe and repeats the above process. FIG. 13 teaches additional detail regarding probe verification usage and related database operations. Periodically controller 401 performs the above verification to alert practitioner that he/she has forgotten to change probe(s).

During the procedure (FIG. 10), various parameters such as peak temperature 1473, power 1472, impedance, etc. . . . are read, scaled, stored and displayed. Parameters such as procedure start 1467; end time 1468, serial number 1469, and part number 1468 are recorded as well. Critical parameters are written to local high-speed memory 438 for display and analysis. On a time permitting or end of procedure, data is mirrored to removable USB 1320 memory stick 1338. Probe specific parameters 1463 are copied and written to probe memory 1338 for use at probe refurbishment facility. Database checksum/CRC(s) 1449, 1479, and 1499 are check and updated as required. Faults such as shorts (dielectric 305 (FIG. 3) breakdown) that are detected are saved to error field 1494 and 1474. If network connection 1305 is available, email request for replacement probe are automatically sent to repair/customer service center 1308. Defective probe 374 with saved failure information 1494 is returned for credit and repair.

Use of a USB memory stick permits continued operation in the event of a network 1326 failure Data is loaded to memory 1338 for simple transfer to office computer 1306 (FIG. 1) for backup. Commonly available USB memory sticks 1320 have large data capacities in the tens to hundreds of megabytes at a low cost with long retention times. USB memory sticks also can support data encryption for secure transfer of patient data. Sealed versions are available as well compatible with chemical sterilization procedures.

If computer network 1326 such as Ethernet 802.11 or wireless 802.11x is available, files are mirrored to local storage 1309, remote server 1307. The remote server (typically maintained by equipment manufacture) can be remotely update procedure(s). To insure data integrity and system reliability a high availability database engine made by Birdstep of Americas Birdstep technology, Inc 2101 Fourth Ave. Suite 2000, Seattle Wash. is offered as an example. The Birdstep database supports distributed backups, extensive fault and error recovery while requiring minimal system resources.

FIG. 11—Patient/Procedure Database 1430

From a touch screen, the practitioner selects or enters patient name from previous procedure 1430 and creates a new record 1433. Similarly, a procedure is selected from 1410 (for example “TEMPORARY NERVE CONDUCTION” 1411, “SMALL TUMOR 1CC” 1412, and “SMALL NERVE ABLATE” 1413). Each procedure has a unique procedure code 1416 that is used for the billing system. Other information such as practitioners name 1440, date 1435 is entered to record 1433. As taught above probe appropriate for the procedure is connected and verified, part 1470 and serial number 1469 recorded.

FIG. 11—Voice and Notes

The practitioner enters additional text notes to file 1442 or records them with microphone 455 (FIG. 5) to wave file 1445 for later playback or transcription. The instant invention permits temporary/permanent nerve conduction interruption. Thus, procedures are performed at intervals from months to years apart. A hands free integrated voice recorder is extremely useful. Detailed text and voice notes made while probing/ablating are also recording specific settings, and patient response. A feature that is very helpful when reviewing treatment progress and saves valuable time instead of writing notes. Practitioners play back voice/wave files 1445 with standard audio tools a his/or hers desk. Audio files 1445 can be sent via email or file transfer for transcription, updating note field 1442.

At the end of procedure, records are updated and stored to memory 438. Backup copies are written to USB 1320 memory stick 1338 (FIG. 1). If computer network 1326 such as Ethernet 802.11 or wireless 802.11x is available, files are mirrored to local storage 1309, remote server 1307. Patient name 1436, procedure date 1435, and procedure codes 1416 are automatically transferred via network or USB device 1320 to billing system 1306. USB memory stick permits continued operation in the event of a network 1326 failure. Data is loaded to USB memory 1338 for simple transfer to office computer 1306 (FIG. 1) for backup. USB memory sticks 1320 have large data capacities in the tens to hundreds of megabytes at a low cost with long retention times. USB memory stick also support data encryption for secure transfer of patient data. Insuring patient is accurately billed with minimal office paper work. Probe inventory is automatic maintained with replacement probes automatic shipped as needed.

Alternative Probe Configurations

FIG. 12 is a schematic view of an alternative embodiment of a single axis electrosurgical probe 2000 having a longitudinal probe axis 2001, which is similar to the probe of FIG. 3. However, probe 2000 of FIG. 12 features substantially equal surface area conductive electrodes 2002 and 2004 located along a longitudinal axis. A probe 371 also having substantially equal surface area electrodes 301 and 302 is shown in FIG. 3A.

In an equal electrode surface area implementation, one of the conductive electrodes 2002, 2004 may be selectively connected to a stimulation current source or an ablation current source as described above. The other electrode 2002, 2004 may be unconnected or connected as a ground or return path for the connected current source. In the embodiment shown in FIG. 12 conductive electrode 2002 is configured to be connected to the ablation source making electrode 2002 the active electrode. Thus electrode 2004 is in this embodiment a return electrode. Either electrode 2002, 2004 may be connected to a current source or return with appropriate switches.

Since electrodes 2002 and 2004 have substantially equal surface area, the local heating formed upon the application of RF ablation energy to the active electrode 2002 results in a heating zone having a substantially symmetrical ellipsoid form.

The single axis electrosurgical probe 2000 of FIG. 12 also features a dielectric insulator 2006 positioned along the probe axis between the conductive electrodes 2002 and 2004. The dielectric insulator 2006 may have any suitable length, and probes with alternative length insulators may be manufactured for specific ablation procedures. Varying the length of the dielectric insulator 2006 varies the gap dimension 2008 between the electrodes 2002 and 2004. Varying the gap dimension 2008 provides for optimization of the current density within the ablation zone, varies the length of the ablation zone and permits the use of higher voltages, if desired. Thus, the gap dimension may be selected in conjunction with other parameters such as electrode surface area and ablation current to achieve select ablation volumes and tissue temperatures for specific applications.

The probe 2000 of FIG. 12 also features a blunt tip 2010 rather than the conical tip 351, chiseled tip 352 or other tips of FIG. 3. The blunt tip 2010 of FIG. 12 has a smooth rounded profile and is advantageous in certain instances to allow the probe to be easily advanced and maneuvered under the skin minimizing the risk of puncture or the cutting of adjacent tissue or anatomical structures. Thus, a blunt tip 2010 may significantly reduce the bruising or other trauma associated with a procedure.

The probe 2000 of FIG. 12 may include a sensor 2012. The sensor may be a temperature sensor 2012. A temperature sensor provides for active temperature monitoring within the ablation zone. Alternatively, a single axis electrosurgical probe of any configuration may be implemented with a Kalman filter as taught by Conolly U.S. Pat. No. 6,384,384 which patent is incorporated herein by reference in its entirety. Kalman filters are also used to estimate tissue temperature within an ablation volume. Kalman filters are suitable for use where well-defined tissue state changes occur at specific temperatures due to protein denaturation such as the denaturation of collagen at 65 C. Kalman filter temperature monitoring is advantageous because the bulk and cost of a separate temperature sensor can be avoided.

FIG. 13 is a schematic view of an asymmetrical single axis probe 2014 also defining a longitudinal probe axis 2015. The probe 2014 features a first conductive electrode 2016 and a second conductive electrode 2018 having different surface areas. In the embodiment shown in FIG. 13, the first electrode 2016 is an active electrode and the second electrode 2018 having a larger surface area is a return electrode. A probe having any surface area ratio between an active and return electrode may be fabricated and used to achieve specific ablation results. In addition, the relative positions of the active electrode 2016 and the return electrode 2018 with respect to the tip of a given probe may be switched. In one embodiment the ratio of the active electrode 2016 to the surface area of the return electrode 2018 is 1:3. Other ratios including 1:8 may be implemented to achieve specific results. The surface area ratio may further be adjustable using a sleeve or other mechanism which will shield or cover a portion of on or both electrodes thus increasing or decreasing the length of the gap defining dielectric insulator 2019. Generally, asymmetrical electrode surface areas will result in asymmetrical heating and ablation because of the higher current density of the RF ablation energy at the electrode with smaller surface area. For example, upon the application of RF energy to the active electrode of the FIG. 13 embodiment, a tissue volume proximal the active electrode 2016 may be asymmetrically heated due to the greater current density resulting from the relatively small surface area of the active electrode 2016. Asymmetrical tissue heating coupled with precise RF power integration taught herein and various probe geometries permits the formation of selected repeatable and controlled ablation volumes.

FIG. 14 schematically illustrates an alternative asymmetrical probe 2020, which is similar in many respects to the asymmetrical probe 2014 of FIG. 13. The asymmetrical probe 2020 of FIG. 14, however, features an active electrode 2022 having a surface area greater than that of the return electrode 2024. In the FIG. 14 embodiment current density is higher at the relatively smaller surface area electrode 2024, thus ablation energy is concentrated in the dielectric insulator gap 2025 between the electrodes 2022 and 2024 nearer return electrode 2024 and away from the tip of the probe.

FIG. 15 is a schematic view of one embodiment of a multiple electrode probe 2026. The multiple electrode probe 2026 includes a substantially needle-shaped probe body 2028 which defines a longitudinal probe axis 2029. More than two electrodes are associated with the probe body and positioned at various locations along the probe axis. In the FIG. 15 embodiment the electrodes include an active electrode 2030, a return electrode 2032, and a stimulation electrode 2034. In this embodiment the active electrode is positioned near the tip of the multiple electrode probe 2026, the return electrode 2032 is positioned away from the tip and the stimulation electrode 2034 is positioned between the active electrode 2030 and the return electrode 2032. It should be noted that the position of the various electrodes with respect to each other and the tip may be varied to achieve specific ablation and probe positioning advantages. In addition, the connection of any given physical electrode as an active electrode, return or stimulation electrode may be varied at the discretion of the user with a simple switching mechanism between the electrode and the ablation or stimulation energy sources. Alternatively, a separate ground or return path 2035 may be utilized with any configuration of electrodes. The various electrodes of the multiple electrode probe 2026 are separated by a first dielectric insulator 2036 and a second dielectric insulator 2038. FIG. 16 schematically illustrates the multi-polar probe 2026 of FIG. 15 with the addition of a curved section 2040 opposite the portion of the probe body 2028 associated with the electrodes. The curved section 2040 may in certain instances allow the practitioner to achieve optimal probe positioning with a minimum of unnecessary tissue disruption. A multiple electrode probe 2026 may be implemented with dielectric insulators 2036, 2038 of varying dimensions, sensors or electrodes of different surface areas, all as described above, to achieve desired ablation results.

FIG. 17-19 schematically illustrates an alternative embodiment of a multiple electrode probe 2042. The multiple electrode probe 2042 of FIG. 17-19 includes a probe body 2044 which defines a longitudinal probe axis 2045. Multiple electrodes 2046-2062 are associated with the probe body 2044 at separate locations along the probe axis. In the embodiment shown in FIG. 17-19 the electrodes are uniformly sized and spaced. It is important to note, however, that different sizes of electrodes and non-uniform spacing of the electrodes may be implemented to achieve specific ablation results. Preferably, each of the electrodes 2046-2062 may be selectively connected with one or more switches to a stimulation current source, an ablation current source, a ground for the stimulation current source a ground for an ablation energy source or left unconnected. As described in detail below, the flexibility provided by switched connection of each electrode to a current source or ground provides certain advantages in probe location and ablation. In addition, the multiple electrode probe 2042 could be deployed in conjunction with a separate return electrode 2064, typically placed in contact with tissue away from the ablation site.

Placement Methods

Several methods of properly positioning a probe adjacent to a selected nerve for ablation energy application are discussed above. For example, probe placement methods featuring florescence marker dyes, optical probe guidance and electronic probe guidance with the use of low energy nerve stimulation current are discussed in detail. Certain of the alternative probe configurations as illustrated in FIGS. 13-19 provide for refined probe placement methods using variations of the basic electrical stimulation techniques described above.

The single axis electrosurgical probe 2000 of FIG. 12 or the asymmetric probes 2014, 2020 of FIG. 13 and 14 may each be properly positioned using an iterative technique, as described above with reference to FIGS. 5A-C. The iterative placement method may be refined for uses with multiple electrode probes such as are depicted in FIGS. 15-19.

For example, the FIG. 15 embodiment of a multiple electrode probe 2026 includes a separate stimulation electrode 2034. The stimulation electrode 2034 is located along the longitudinal axis 2029 of the probe body, typically though not necessarily between an active electrode 2030 and a return electrode 2032. During the stimulation and positioning phases of a probe placement procedure the active electrode 2030, return electrode 2032 or a separate electrode 2035 not associated with the probe body 2028 may serve as the ground for the stimulation current source. As is described above with respect to FIG. 5 a practitioner will typically monitor target nerve response by observing muscle reaction elicited by the stimulation current as the multiple electrode probe 2026 is iteratively guided closer to the target nerve 101. The level of stimulation currently applied may be adjusted to increase or decrease the effective stimulation range depending upon the muscle response observed by the practitioner. Typically, stimulation current will be continuously or stepwise reduced with a switch or other control to decrease the stimulation range as the stimulation electrode 2034 is guided in close proximity to the subject nerve 101, assuring that the nerve is ultimately placed adjacent to the stimulation electrode.

In probe embodiments where the stimulation electrode is positioned in between the ablation electrodes 2030, 2032, the above described iterative method guarantees that the target nerve is positioned within an elliptical ablation zone 2064 (see FIG. 16) which will be formed between the active electrode 2030 and return electrode 2032 upon the application of RF ablation energy.

FIG. 17-19 shows an alternative embodiment of a multiple electrode probe 2042 placed in various orientations with respect to a target nerve 2066. For example in FIG. 17, the multiple electrode probe 2042 is placed transverse the nerve 2066, in FIG. 18 the multiple electrode probe 2042 is placed parallel to a portion of the nerve 2066 and FIG. 19 shows the multiple electrode probe 2042 placed across the target nerve 2066 at an angle. As is described in detail above, each of the electrodes 2046-2065 may preferably be selectively connected to a stimulation current source, an ablation energy source, a ground or left unconnected. The electrodes 2046-2062 may be connected manually or switched and activated electronically.

The multiple electrodes of the FIG. 17-19 embodiment of the multiple electrode probe 2042 provides for certain advanced placement and ablation procedures. For example, FIG. 17 illustrates a method for locating and selectively ablating a target nerve 2066, which runs substantially transverse the probe at a point along the axial length of the probe 2042. This placement method features the practitioner initially positioning the probe across the target nerve 2066. The electrodes 2046 through 2062 are then activated sequentially with stimulating current, in adjacent active/ground pairs (bipolar mode) or individually with reliance upon an external ground 2064 (mono-polar mode). The practitioner may then observe the response of one or more muscles associated with the target nerve as stimulation current is applied to successive electrodes 2046-2062.

For example, with reference to FIG. 17, stimulation current may be applied between electrodes 2046 and 2048. The practitioner notes that there is no corresponding muscle response. Stimulation current may next be applied between electrodes 2048 and 2050. Again, no muscle response is observed by the practitioner. Sequentially, stimulation current is then applied to successive electrode pairs. When the stimulation current is applied between electrodes 2054 and 2056 there may be a mild muscle response. When the stimulation current is applied between electrodes 2056 and 2058 however, a strong muscle response will be observed. Continuing on, the stimulation is then applied between electrodes 2058 and 2060. Here a greatly reduced muscle response is observed indicating that the nerve is crossing the probe substantially between electrodes 2056 and 2058. Subsequently, ablation energy may be applied between designated electrodes 2056 and 2058 to ablate nerve 2066.

FIG. 18 illustrates a similar nerve location and ablation procedure wherein the nerve 2066 is substantially parallel to and adjacent to the axial length of the probe 2042 adjacent electrodes 2048 through 2056. In this second example the practitioner first applies stimulation current is applied between electrodes 2046 and 2048. A mild muscle response or no muscle response may be observed. When stimulation current is applied between electrodes 2048 and 2050, a strong muscle response is noted by the practitioner.

Sequentially, the stimulation current is then applied between electrodes 2050 and 2052 with similar strong muscle response observed. This sequential stimulation and response process is observed through the activation of electrodes 2056 and 2058 where the muscle response is substantially diminished or not observable. This is an indication that electrodes 2048 through 2056 are all in contact with the nerve 2042. The electrodes 2048 through 2056 may then be switched to the ablation current source activated and sequentially or simultaneously in bi-polar pairs or individually in bi-polar or mono-polar mode to ablate the nerve 2042. The nerve could be ablated along a select length defined by the number of electrodes activated by the practitioner. This method could also be implemented in mono-polar mode whereby stimulation or ablation energy is applied between one or more electrodes 2046 through 2062 and a separate return electrode applied externally on the body.

FIG. 19 illustrates a substantially similar nerve location and ablation procedure wherein the multiple electrode probe 2042 crosses the nerve 2066 diagonally or at an oblique angle to the probe axis. Thus, FIG. 19 illustrates a method for angular positioning of the probe 2042 relative to the nerve 2066. In this example stimulation current applied as described above at electrodes 2052, 2054, and perhaps 2056 would result in a response in the associated muscle. If a larger number of electrodes elicit a muscle response, this is an indication of a broader nerve/probe contact area resulting from a more parallel contact placement of the probe 2042 relative to the nerve 2066. Such a determination of angular placement can be enhanced by fabricating a probe with relatively short distance between adjacent electrodes, relative to the diameter of a nerve of interest. The practitioner may also maneuver the probe to attain a muscle response from more or less electrodes as desired providing the opportunity to ablate a greater or lesser length of the never without axially repositioning the probe.

The above methods of angular probe positioning and sequential stimulation may be combined with the iterative techniques also described above. For example, the stimulation current generator may be set at a relatively high level initially and reduced when the general location of the nerve with respect to certain electrodes is determined.

For example, the stimulation current threshold (to elicit an observable response) between electrodes 2048 and 2050 of FIG. 19 would be higher than the threshold between electrodes 2050 and 2053. This information could be indicated graphically, numerically or audibly to allow the practitioner to reposition the probe for more parallel or more transverse positioning of probe 2042 relative to nerve 2066.

While the invention has been particularly shown and described with reference to a number of embodiments, it would be understood by those skilled in the art that changes in the form and details may be made to the various embodiments disclosed herein without departing from the spirit and scope of the invention and that the various embodiments disclosed herein are not intended to act as limitations on the scope of the claims. 

1. An electrosurgical probe comprising: a probe body defining a longitudinal probe axis; and a first and a second conductive electrode operatively disposed along the probe axis wherein the surface area of the first conductive electrode is substantially greater than the surface area of the second conductive electrode.
 2. The electrosurgical probe of claim 1 wherein a ratio of the surface area of the first conductive electrode to the surface area of the second conductive electrode is equal to or greater than 3:1.
 3. The electrosurgical probe of claim 1 wherein a ratio of the surface area of the first conductive electrode to the surface area of the second conductive electrode is equal to or greater than 8:1.
 4. The electrosurgical probe of claim 1, wherein a ratio of the surface area of the first conductive electrode to the surface area of the second conductive electrode is adjustable.
 5. The electrosurgical probe of claim 1 further comprising a stimulation energy source in electrical communication with at least one of the first or second conductive electrodes.
 6. The electrosurgical probe of claim 5 further comprising an ablation energy source in electrical communication with at least one of the first or second conductive electrodes.
 7. The electrosurgical probe of claim 6 further comprising a switch providing for the selective connection of the stimulation energy source or the ablation energy source to at least one of the conductive electrodes.
 8. An electrosurgical probe comprising: a probe body defining a longitudinal probe axis; an active electrode operatively associated with the probe body at a first location along the probe axis; a stimulation electrode operatively associated with the probe body at a second location along the probe axis; and a return electrode operatively associated with the probe body at a third location along the probe axis.
 9. The electrosurgical probe of claim 8 wherein the stimulation electrode is positioned along the probe axis between the active electrode and the return electrode.
 10. The electrosurgical probe of claim 8 further comprising a stimulation energy source in electrical communication with the stimulation electrode.
 11. The electrosurgical probe of claim 10 wherein the stimulation energy source provides variable stimulation current.
 12. The electrosurgical probe of claim 10 wherein at least one of the active electrode and the return electrode is in electrical communication with a ground for the stimulation energy source.
 13. The electrosurgical probe of claim 10 wherein both of the active electrode and the return electrode are in electrical communication with a ground for the stimulation energy source.
 14. The electrosurgical probe of claim 7 further comprising an ablation energy source in electrical communication with the active electrode.
 15. The electrosurgical probe of claim 13 wherein the ablation energy source provides variable ablation energy.
 16. The electrosurgical probe of claim 15 wherein the ablation energy source provides energy which has at least one of variable voltage, current and waveform.
 17. An electrosurgical probe comprising: a probe body defining a longitudinal probe axis; at least three electrodes operatively associated with the probe body at separate locations along the probe axis; and a stimulation energy source in electrical communication with at least one of the electrodes.
 18. The electrosurgical probe of claim 17 wherein the stimulation energy source provides variable stimulation energy.
 19. The electrosurgical probe of claim 17 wherein the stimulation energy source may be selectively connected to at least one or more of the electrodes.
 20. The electrosurgical probe of claim 17 further comprising a stimulation energy ground in electrical communication with the stimulation energy source, wherein the stimulation energy ground may be selectively connected to at least one or more of the electrodes.
 21. The electrosurgical probe of claim 17 further comprising an ablation energy source in electrical communication with at least one of the electrodes.
 22. The electrosurgical probe of claim 21 wherein the ablation energy source provides variable ablation energy.
 23. The electrosurgical probe of claim 22 wherein the ablation energy source provides energy which has at least one of variable voltage, current and waveform.
 24. The electrosurgical probe of claim 21 wherein the ablation current source may be selectively connected to at least one or more of the electrodes.
 25. The electrosurgical probe of claim 21 further comprising an ablation energy ground for the ablation energy source, wherein the ablation energy ground may be selectively connected to one or more of the electrodes.
 26. A method of positioning an electrosurgical probe comprising: providing an electrosurgical probe having a probe body defining a longitudinal probe axis, multiple conductive electrodes operatively disposed along the probe axis, and a stimulation energy source in electrical communication with at least one of the conductive electrodes; inserting the electrosurgical probe to a first position within tissue containing a target nerve; applying first stimulation energy to the stimulation electrode; observing a first response of a muscle associated with the target nerve; moving the electrosurgical probe to a second position within the tissue containing the target nerve; applying second stimulation energy to the stimulation electrode; observing a second response of a muscle associated with the target nerve; and comparing the second response of the muscle associated with the target nerve to the first response of the muscle associated with the target nerve.
 27. The method of claim 26 further comprising: providing a variable stimulation energy source; and varying the stimulation energy between the first and the second applications of stimulation energy.
 28. A method of positioning an electrosurgical probe comprising: providing an electrosurgical probe having a probe body defining a longitudinal probe axis, multiple conductive electrodes operatively disposed along the probe axis, and a stimulation energy source which may be connected sequentially to more than one of the conductive electrodes; inserting the electrosurgical probe into tissue containing a target nerve; applying stimulation current to a select first electrode; observing a first response of a muscle associated with the target nerve; applying stimulation energy to a select second electrode; observing a second response of the muscle associated with the target nerve; and comparing the second response of the muscle associated with the target nerve to the first response of the muscle associated with the target nerve.
 29. The method of claim 28 further comprising: applying stimulation energy to a select third electrode; observing a third response of the muscle associated with the target nerve; and comparing the third response of the muscle associated with the target nerve to the second response of the muscle associated with the target nerve.
 30. The method of claim 29 further comprising sequentially applying stimulation energy to the first, second and third electrodes. 